1. Field of the Invention
This invention relates to a two wire transmitter where the DC excitation to the transmitter is amplitude controlled in response to a varying reactance such as a capacitance pressure sensor so that the DC current serves both as excitation and as the electrical signal representative of the sensed pressure.
2. Description of the Prior Art
Two wire circuitry for converting a varying AC reactive impedance to a current signal is described in my U.S. Pat. No. 3,646,538 and this disclosure shows certain improvements over that prior disclosure.